2Essential Knowledge2.e.2 – Timing and coordination of physiological events are regulated by multiple mechanisms (11.1).3.b.2 – A variety of intercellular and intracellular signal transmissions mediate gene expression (11.1 & 11.4).3.d.1 – Cell communication processes share common features that reflect a shared evolutionary history (11.2 & 11.2).3.d.2 – Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling (11.1 & 11.2).
3Essential Knowledge3.d.3 – Signal transduction pathways link signal reception with cellular response (11.3).3.d.4 – Changes in signal transduction pathways can alter cellular response (11.4).
4IntroductionEndocrine system deals with chemical control and communicationUses hormonesHormone: chemical signal usually transported through bloodstream, elicits a specific response from target cellProduced by endocrine cells (neurosecretory cells)Specialized nerve cellsHormones regulate activity of other cells and organsHormones bind to cell surface receptors
6Introduction Hypothalamus and pituitary gland coordinate Produce many hormones that control production of other hormones in other endocrine glands/organsNervous system: coordinates and communicatesEndocrine system: produces hormones which regulate bodily processes
7Pathways for signals A receptor/sensor detects a change (stimulus) Receptor notifies the control centerControl center sends out an efferent signal which directs a response by effectorEndocrine cells: acts as both sensor and control centerSends out either hormones or signalUsually controlled via negative feedback loop
8Hormones Three groups/classes of hormones: Types of signals: Peptide/Protein (water-soluble)Amine (water-soluble)SteroidTypes of signals:Hormones: within body (long distance)Local regulators: neighboring cellsPhermones: communication between individual organisms
10Hormones Hormones bind to target cell receptors Initiate pathways/signals that end in specific cell responsesSteps of signal response:Reception: Signal binds to specific protein receptor on target cellSignal transduction: signal’s message is transmitted via target cellResponse: the end result, how the target cell responds
12HypothalamusHypothalamus and pituitary integrate the endocrine system functionsHypothalamus:Situated in lower brainIntegrates endocrine and nervous systemReceives nerve signals from bodyIt’s neurosecretory cells release hormonesThese hormones are stored in or regulate by the pituitary gland
14Pituitary gland Pituitary gland: Located at the base of hypothalamus Regulate and stores hormones produced by hypothalamusTwo parts:Posterior: stores and secretes two hormones from hypothalamusAnterior: makes at least 6 hormones (tropic hormones), important to chemical coordination
16Hormone examples Antidiuretic hormone (ADH) Oxytocin Functions in osmoregulationIncreases water retention by kidney (decreases urine volume)Produced in posterior pituitaryOxytocinInduces uterine contractions during birthInduces milk ejection during nursingThyroid-stimulating hormone (TSH)Regulates production of thyroid hormonesProduce in anterior pituitary gland
17Hormone examplesFollicle-stimulating hormone (FSH) and luteinizing hormone (LH):Stimulate gonad activityProduced in anterior pituitaryProlactin (PRL)Mammals: milk production and secretionAmphibians: delays metamorphosisFish: osmoregulationEndorphin:Pain perceptionCan resemble opiate drugs (giving you a sense of well-being!)
18Hormone examples Growth hormone (GH): IGFs: T3 and T4: Variety of target tissuesSignals release of IGFs (Insulin-like growth factors)Gigantism (human growth disorder caused by excessive GH)Produced by anterior pituitaryIGFs:Produced by liverStimulate bone and cartilage growthT3 and T4:Produced by thyroid glandSecretion controlled by negative feedbackCritical to development and maturation
19Hormone examples T3 and T4, cont.: Blood calcium hormones: Contributes to homeostasisMaintain normal blood pressure, heart rate, muscle tone, digestion, reproductive functionBlood calcium hormones:Parathyroid hormone (PTH): stimulate Calcium resabsorption in kidney, activate vitamin D which helps uptake of Ca in intestinesCalcitonin: hormone that lowers calcium levels in blood
20Hormone examples Blood glucose hormones: Glucagon: raises glucose concentrations by stimulating liver to increase breakdown of glycogenInsulin: lowers glucose concentration by promoting movement of glucose from blood into other body cellsProduced by pancreatic cellsDiabetes mellitus: absence of insulin in bloodstream or loss of response to insulinType-I: autoimmune disorder, treated by regular insulin injectionsType-II: 90% of diabetics, insulin deficiency, controlled via exercise and diet control
21Hormone examples Stress hormones: Gonadal sex hormones: Epinephrine (adrenaline)Norepinephrine (noradrenaline)Sustain blood pressureProduced by adrenal glandsIncrease availability of energy sourcesIncrease metabolic rateGonadal sex hormones:Produces by testes and ovariesAffect growth, development and reproductive cycles and behaviors
22Epinephrine works on the sympathetic ½ of nervous system
23Hormone examples Gonadal sex hormones, cont.: Three groups: Androgens: Produced primarily by testesEx: testosterone (determines gender, stimulate development of male reproductive system)EstrogensProduced by ovariesRegulate development and maintenance of female reproductive systemProgestinsHelp prepare and maintain uterus for growth of embryo
25Hormone examples Melatonin: Secreted and produced in pineal gland (near center of brain)Regulate functions related to light and changes in day lengthSecretion at night functions with biological clock for daily or seasonal activities (such as sleeping, mating, nesting)
27Exclusion StatementsMemorization of the names, molecular structures, and specific effects of hormones or features of the brain are responsible for these physiological phenomena is beyond the scope of the course and the AP Exam.